Rotary countercurrent solid-liquid extraction apparatus

ABSTRACT

A METHOD FOR EXTRACTING, BY MEANS OF A LIQUID, PRODUCTS WHICH ARE PART OF SOLIDS IN A PARTITIONED ROTATING EXTRACTOR, WITH THE FLOW OF THE LIQUID FRACTION SEPARATED FROM THE SOLIDS FRACTION BEING SLOWED DOWN BY BAFFLES AND SAID LIQUID FRACTION BEING SPREAD OVER THE LENGTH AND WIDTH RELATIVE TO THE NEW SOLIDS FRACTION.

y 7, 1974 G. F. DUCHATEAU 3,809,538

ROTARY COUNTERCURHENT SOLID-LIQUID EXTRACTION APPARATUS Filed June 28,1971 1] \7 4 Sheets-Sheet 1 May 7, 1974 G. DUCHATEAU 8 ROTARYCOUNTERGURRENT SOLID-LIQUID EXTRACTION APPARATUS Filed June 28, 1 971 4Sheets-Sheet 3 1'0 v v m\ m m L a .1 a 1 n l n m u u w m rllk llll I...Ill-lullllilll n w \1 r l l |||\||L 1 l IJIIINIIIIII m m y 7, 1974 G. F.DUCHATEAU 3,809,538

ROTARY COUNTERCURRENT SOLID-LIQUID EXTRACTION APPARATUS Filed June 28,1971 4 Sheets-Sheet 5 y 7, 1974 s. F. DUCHATEAU 3,809,538

ROTARY COUNTERCURRENT SOLID-LIQUID EXTRACTION APPARATUS Filed June 28,1971 4 Sheets-Sheet 4 United States Patent 3,809,538 ROTARYCOUNTERCURRENT SOLID-LIQUID EXTRACTION APPARATUS Georges F. Duchateau,Tienen, Belgium, assignor to Ratfinerie tirlemontoise, Brussels, BelgiumFiled June 28, 1971, Ser. No. 157,224 Claims priority, applicationLuxemburg, July 3, 1970, 61,261/ 70 Int. Cl. B01d 11/02 US. Cl. 23-269 9Claims ABSTRACT OF THE DISCLOSURE A method for extracting, by means of aliquid, products which are part of solids in a partitioned rotatingextractor, with the flow of the liquid fraction separated from thesolids fraction being slowed down by bafiles and said liquid fractionbeing spread over the length and width relative to the new solidsfraction.

This invention relates to improvements in methods for extracting, bymeans of a liquid, products which are part of solids in a partitionedrotating extractor in which the solids on the one hand and the liquid onthe other hand are divided into fractions with relative resultinglengthwide displacements along opposite directions, each liquid fractionbeing periodically separated from a solids fraction and said fractionthen flowing toward another solids fraction.

Methods of this kind and devices for the working thereof are alreadyknown, notably from Belgian Pat. Nos. 367,630, 371,926, 475,626, 711,219and 728,417. It has been noted that the mixture of the liquid fractionand the solids fraction was not homogeneous and that the common path inthe extractor did not correct said lack of homogeneity, because theliquid or solids fraction was not from the start in proportion withsolids or liquid fraction supply and was not suitably distributed overthe length and width.

An object of this invention is to obviate these drawbacks. For thispurpose according to the invention, the flow of the liquid fractionseparated from the solids fraction is slowed down and said liquidfraction is spread over the length and width relative to the solidsfraction.

A further object of this is to improve the extracting devices for theworking of said improved method. Such devices comprise a rotating druminside which is arranged a screw conveyor the solid windings of whichdefine compartments for the solids fractions and the liquid fractions,said compartments being subdivided into cells which contain the solidsfractions, said cells communicating for the liquid through generallyaxial raising elements for the solids, said elements being pervious tothe liquid and extending between two succeeding windings. According tothe invention, each cell comprises a bafile for slowingdown the inletliquid flow in said cell, which baflle is arranged as considered alongthe liquid movement direction in the drum, downstream of the raisingelement of that cell the liquid fraction flows from.

In a preferred embodiment, said bafile extends generally axially betweenthe windings which bound the cell on the liquid inlet side of the cell,from the drum circumference over a radial distance relative to the drumaxis which ie at least equal to the distance occupied in the cell by thesolids and liquid fractions.

Other detail and features of the invention will stand out from thedescription given below by way of non-limitative examples and withreference to the accompanying drawings, in which:

FIG. 1 is a diagrammatic view, with parts broken away, of a length ofextracting device as described in "ice Belgian Pat. No. 475,626, alongarrow A in FIG. 2, which device is provided with the improvementaccording to the invention.

FIG. 2 is a diagrammatic section view along the line BB in FIG. 1.

FIG. 3 is a diagrammatic plan view on a larger scale, of FIG. 2.

FIG. 4 is a diagrammatic view with parts broken away, of an extractingdevice of the type described in Belgian Pats. No. 711,219 and 728,417along arrow C in FIG. 5, showing the improvement according to theinvention.

FIG. 5 is a diagrammatic section view along line D-D in FIG. 4.

FIG. 6 is a diagrammatic plan view, on a larger scale, corresponding toFIG. 5.

FIG. 7 is a view similar to FIG. 2 showing another embodiment.

In the various figures, the same reference numerals pertain to similarelements.

FIGS. 1 and 4 each slow a length of a device for extracting with aliquid products which are part of solids, the liquid and solids havingresulting relative displacements along opposite directions. Suchextracting devices, which are notably well known in the sugar industry,comprise in the embodiment shown in FIGS. 1 to 3, an horizontal-axisdrum 1 which is rotatable along the direction of arrow 2, said drumbeing divided into compartments by a conveyor screw which is comprisedof a series of portions of diametral solid walls 3 which are connectedby portions of slanting solid walls 4. The compartments are subdividedinto two series of cells I, I", II, II" by solids-raising elements 5which are previous to the liquid and comprised of perforated baskets thebottoms 6 of which are generally axial and are joined in pairs by asolid axial wall 7. Two series of slants channels 8, 8' are provided inthe central area of the drum 1 to direct the solids fractions raised bythe baskets 5 as they pass through the lower part of the drum inside acell of one and the same series, which is spaced along a directionopposite to the screw conveying direction, which opposite direction isshown by arrow 25, by two cells relative to a particular cell; forinstance the solids fraction raised by the basket in cell II will fallin cell IV.

The liquid fractions separated from the solids raised by the baskets 5each flow in the cell of the other series which, when considering thedrum rotating direction, lies directly upstream of the cell the fractionleaves so as to mix with a new solids fraction with which it is conveyedalong the screw conveying direction (direction opposite to the arrow 25)till the raising thereof by the basket of said other series cell;consequently the liquid fraction passing through the basket of cell IIflows in cell II.

To spread uniformly the liquid fraction which is each time separatedfrom a solids fraction relative to the width and the height of the newsolids fraction said liquid fraction will meet in the new cell and toslow down the liquid flow in the new cell, in each cell I, I, II, II",is provide a baiile 9 which extends when considering the drum rotatingdirection, upstream and when considering the liquid conveying directionin the drum, downstream of the bottom 6 of the basket 5 of that cellwhich the liquid fraction leaves each time to reach the cell underconsideration.

By width and height of a solids fractions is meant the space which saidfraction occupies when it lies in the drum lower part, on the one handalong the drum axial direction and on the other hand along the drumradial direction.

The bafiles 9 are comprised of irregularly-perforated walls which extendaxially between each two succeeding walls 3 substantially in parallelrelationship with the bottom 6 of the baskets 5 and radially from thedrum peripheral wall over a distance at least equal to the length of thebasket bottoms 6. Lengths of solid walls 11 join the bafiles 9 to theaxial walls 7.

The ratio between the perforated area and the solid area of the walls 9increases from the peripheral wall of the drum 1 towards the drum axis;preferably the perforation area increases with the distance from thedrum peripheral wall.

In the embodiment shown in FIGS. 7, the irregularlyperformated bafile 9is placed by a baffle with solid portion 9 adjacent to the drumperipheral wall and followed by a chain bed 9". According to thisembodiment an actual delay is introduced between the time where liquidfraction flow from a cell starts and the time where this liquidcollected behind the baffle solid portion flows in the new cell.

In the device shown in FIGS. 4 to 6 which is of the type disclosed inBelgian Pats. No. 711,219 and 728,417, the drum rotating direction isshown by arrow 10 and the screw conveyor windings comprised of a seriesof cut-out solid diametral walls 11 which are joined by slanting solidwalls 12, insure the conveying of the solids along the direction ofarrow 13. A solid axial wall 14 which extends between the succeedingwalls as well as diametrically-opposed baskets 15 divide thecompartments defined by the windings into two series of cells I, II,III, and I, II, III, for contacting each a solids fraction and a liquidfraction. For the advance of the liquid fractions along the directionopposite to the direction of arrow 13, slanting liquid channels 16 areformed on the circumference of the drum 1 bet-ween the two solid walls17 which extend the axial wall 14 and border notches 18 provided in thesolid diametral walls 11. Each liquid channel 16 opens (inlet) in 16a onthe one hand behind (upstream) the bottom 15a of the basket 15 in eachcell when considering the drum rotating direction and on the other handin 16b in a cell of the other series which is part of the compartmentremoved by two units from that compartment the original cell is part of;for instance with reference to FIG. 6, the liquid fraction leaving cellIII flows in cell I.

According to the invention each cell is provided in such a case alsowith a bafile 19 for slowing down the flow of that liquid fraction whichenters the cell in 1611. Said bafile 19 which is similar to the baflles9 described with reference to FIGS. 1 to 3 and 7, is arranged in theextension of the solid wall 17 which ends at the outlet 16b of theconsidered cell liquid channel 16 over substantially all of the cellwidth; a length of perforated wall 21 joins the bafile to the connectingline between the solid wall 17 in said cell and the winding 11 boundingsaid cell on the side opposite inlet 16a, while another length ofperforated wall joins the high end of the bafile to the axial wall 14 ata level which corresponds substantially to the high end of the bottom15a of that basket 15 pertaining to the opposite-series cell in the samecompartment. It must be understood that the invention is in no waylimited to the above embodiments and that many changes may be broughttherein without departing from the scope of the invention as defined bythe appended claims.

What I claim is: 1. In an apparatus for extracting material from solidsby contacting the solids with counterflowing liquid comprising:

a revolving drum housing means; solid walls means defining at least onesolid conveyor screw means mounted in said revolving drum housing meansand integral with said drum housing means;

said walls determining compartments for fractions of solids and forfractions of liquid;

at liquid permeable solids raising means positioned in each compartment;

means for feeding the solids into said revolving drum housing means at afirst end of said conveyor means and means for removing liquid from saidrevolving drum housing means also at said first end;

means for feeding liquid into said revolving drum housing means at asecond end of said conveyor means opposite to said first and means forremoving solids from said revolving drum housing means also at saidsecond end;

means to convey the fractions of liquid separated by said liquidpermeable solids raising means to successive compartments; and

means for conveying the fractions of solids raised by said liquidpermeable solids raising means to successive compartments but in anopposite resulting direction of displacement in relation to the liquidfractions and without intermixing between the successive fractions ofsolids and between the fractions of liquid the improvement comprising abafile located in at least one of said compartments adjacent to theliquid permeable solids raising means positioned in the precedingcompartment, downstream of said liquid permeable solids raising meanswhen the direction of the liquid flow is considered, and parallel tosaid liquid permeable solids raising means, said baffle being adapted todelay the flow of the liquid fraction and to spread the liquid fractionin relation to a new fraction of solids falling in said compartment froma liquid permeable solids raising means, which baffle extendssubstantially axially between two succesive walls of the conveyor meansand which baflle is provided with passages for the liquid, the area ofsaid passages increasing from the drum circumference toward the drumaxis.

2. In the improvement as claimed in claim 1, the further feature thatsaid baffle comprises a solid portion adjacent to the drum housingmeans, followed by a portion provided with passages for the flow of theliquid.

3. In the improvement as claimed 1, the further feature that said bafilecomprises a solid portion adjacent to the drum housing means followed bya portion comprising a chain bed.

4. In an apparatus for extracting material from solids by contacting thesolids with a counter flowing liquid comprising:

a revolving drum housing means;

a pair of separate stepped helical solid conveyor means, each solidconveyor means carrying a portion of the solids in an axial directionthrough the drum housing in a continual forward motion withoutintermixing or regression;

a central partition extending axially through the drum separating thetwo solid conveyor means, the central partition preventing intermixingof the solids portions, each solid conveyor means further including aseries of successive cells for moving its respective portion of solids;

means for feeding the solids into said revolving drum housing means at afirst end of each solid conveyor means and means for removing liquidfrom said revolving drum housing means also at said first end;

means for feeding liquid into said revolving drum housing means at asecond end of each solid conveyor means opposite to said first end andmeans for removing solids from said revolving drum housing means also atsaid second end;

a liquid-permeable solids raising means positioned in each successivecell; and

liquid conveyor means including channels through the central partitionextending substantially inward from the drum housing means and in theaxial direction for passing liquid in a counter axial direction to thesolids direction, each channel connecting one cell of one solid conveyormeans with a successive cell in the other conveyor means, each channelextending beneath an adjacent cell in the same successive series ofcells as the one cell, whereby the liquid is transmitted in two separateportions and travels twice as fast through the drum as the solidportions, the improvement according to which in at least one of saidcells a baflle is provided to delay the flow of the liquid fractionsentering said cell and to spread the liquid fractions in width andheight with reference to the fractions of solids that falls in said cellfrom the raised elements;

said baflle extends substantially axially between successive helixeswith the helical conveyor means immediately behind, when the directionof rotation of the drum is considered, of the outlet for the liquid ofthe channel in said cell, said bafile being located adjacent to theliquid permeable solids raising means positioned in the precedingcompartment, downstream of said liquid permeable solids raising meanswhen the direction of the liquid flow is considered, and parallel tosaid liquid permeable solids raising means, and

said bafile is provided with passages for the liquid the area of whichincreases from the drum housing towards the drum axis.

5. In an improvement according to claim 4, the further feature that saidbafile comprises a solid portion adjacent to the drum housing means,followed by a portion provided with passages for the flow of the liquid.

6. In an improvement according to claim 4, the further feature that saidbafile comprises a solid portion adjacent to the drum housing meansfollowed by a portion comprising a chain bed.

7. In an apparatus for extracting material from solids by contacting thesolids with a counterfiowing liquid comprising:

a revolving drum housing means;

a pair of separate stepped helical solid conveyor means, each solidconveyor means carrying a portion of liquid in an axial directionthrough the drum housing in a continual forward motion withoutintermixing or regression;

a central partition extending axially through the drum housing means andhaving a central liquid nonpermeable portion and two liquid permeableportions situated adjacent the drum housing means for getting throughthe liquid, said central partition defining on each side thereof aseries of successive cells for moving a respective portion of solids;

a liquid permeable solids raising means positioned in each successivecell;

inclined channels through the helixes of the helical conveyor meansprovided in the central zone of the drum housing means, on each side ofsaid central portion of said central partition for passing solids in acounter-axial direction to the liquid direction, each channel connectingone cell of one series of cells with the successive but one cell of thesame series of cells;

means for feeding liquid into said revolving drum housing means at afirst end of said solid conveyor means and means for removing solidsfrom said revolving drum housing means also at said first end; and

means for feeding the solids into said revolving drum housing means at asecond end of said conveyor means opposite to said first end and meansfor removing liquid from said revolving drum housing means also at saidsecond end;

whereby the liquid is transmitted in two separate portions and travelstwice as fast through the drum as the solid portions without intermixingof the solids portions, the improvement according to which, in at leastone of said cells, a baffle is provided to deay the flow of the liquidfractions entering said cells and to spread the liquid fractions inwidth and in height with reference to the fractions of solids which fallfrom the raising elements into said cells, said baffle extendingsubstantially axially between successive helixes of the helical conveyormeans immediately behind, when the direction of rotation of the drum isconsidered, that liquid permeable portion of the central partition whichis situated in the bottom of the drum housing means when entering of theliquid into the cell is considered, said baffle furthermore beinglocated adjacent to the liquid permeable solids raising means positionedin the preceding compartment, downstream of said liquid permeable solidsraising means when the direction of the liquid flow is considered, andparallel to said liquid permeable solids raising means, and said bafilebeing provided with passages for the liquid, the area of said passagesincreasing from the drum circumference to the drum axis.

8. In an improvement according to claim 7, the further feature that saidbaffie comprises a solid portion adjacent to the drum housing means,followed by a portion provided with passages for the flow of the liquid.

9. In an improvement according to claim 7, the further feature that saidbaflle comprises a solid portion adjacent to the drum housing meansfollowed by a portion comprising a chain bed.

References Cited UNITED STATES PATENTS 3,598,537 8/1971 Kraft 23-272. 63,660,042 5/1972 Duchateau 23-269 2,012,298 8/1935 Berg 23-269 2,337,13712/1943 Thompson 23-269 2,173,546 9/1939 Bowers 23-269 3,297,410 1/1967De Lisle 23-269 2,765,298 10/1956 Signer 23-269 FOREIGN PATENTS 108,36110/1958 Pakistan 23-269 437,803 10/1957 Italy 23-269 WILBUR L. BASCOMB,JR., Primary Examiner S. I. EMERY, Assistant Examiner US. Cl. X.R.

